MiFaZhan
69 lines
1.5 KiB
Go
69 lines
1.5 KiB
Go
package upstreamimpl
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import (
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"context"
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"sync"
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"time"
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)
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const tibiotSimDataMarginInterval = 650 * time.Millisecond
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// tibiotSimDataMarginLimiter spaces requests globally because Tibiot applies
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// the simDataMargin quota to the gateway's public IP, not to a channel.
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var tibiotSimDataMarginLimiter = newTibiotRateLimiter(tibiotSimDataMarginInterval)
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type tibiotRateLimiter struct {
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mu sync.Mutex
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interval time.Duration
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next time.Time
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}
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func newTibiotRateLimiter(interval time.Duration) *tibiotRateLimiter {
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if interval <= 0 {
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interval = tibiotSimDataMarginInterval
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}
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return &tibiotRateLimiter{interval: interval}
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}
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// wait blocks until a slot is available and only consumes the slot when the
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// caller's context is still active. Waiting callers do not reserve future
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// slots, so canceled requests cannot delay later retries.
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func (l *tibiotRateLimiter) wait(ctx context.Context) error {
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if l == nil {
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return nil
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}
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if ctx == nil {
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ctx = context.Background()
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}
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for {
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if err := ctx.Err(); err != nil {
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return err
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}
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l.mu.Lock()
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now := time.Now()
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if !l.next.After(now) {
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// Check again while holding the mutex so a cancellation racing with
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// the slot boundary cannot consume a slot unnecessarily.
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if err := ctx.Err(); err != nil {
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l.mu.Unlock()
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return err
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}
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l.next = now.Add(l.interval)
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l.mu.Unlock()
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return nil
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}
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wakeAt := l.next
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l.mu.Unlock()
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timer := time.NewTimer(time.Until(wakeAt))
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select {
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case <-timer.C:
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case <-ctx.Done():
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timer.Stop()
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return ctx.Err()
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}
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}
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}
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